public void WhenGrantTypeIsNull_ThenThrows()
            {
                dto.GrantType = null;

                Assert.Throws <ValidationException>(
                    FluentValidation <CreateAccessToken> .NotNullErrorMessage(x => x.GrantType),
                    () => validator.ValidateAndThrow(dto));
            }
            public void WhenNameIsNull_ThenThrows()
            {
                var dto = new CreateClientApplication
                {
                    Name = null,
                };

                Assert.Throws <ValidationException>(
                    FluentValidation <CreateClientApplication> .NotNullErrorMessage(x => x.Name),
                    () => validator.ValidateAndThrow(dto));
            }